The only way I can think of is as follows:
Lvl. 1 Starly vs. Lvl. 100 __
[email protected] Sash
The level 100 would have higher speed, so it would move first. It would kill the Starly, but Starly has a focus sash, so it has 1hp left.
Starly uses Endeavor, leaving the level 100 with 1hp as well.
The next turn, Starly uses Quick Attack to kill the opponent.
Can anyone think of other ways?